Lightweight telescoping camera crane

ABSTRACT

A lightweight camera crane has an outer arm pivotally attached to a base. A trim weight tray is rigidly attached to a back end of the outer arm. A moving counterweight carriage is supported on carriage rollers on top of the outer arm. An inner arm is supported on arm rollers within the outer arm. A camera platform is pivotally attached to a front end of the inner arm for tilt axis movement. An electric leveling motor connected to the camera platform via a mechanical linkage keeps the camera platform level regardless of the tilt angle of the camera crane. An electric extension motor drives telescoping extension and retraction movement of the inner arm via chains, belts or cables connected to the counterweight carriage and the inner arm.

BACKGROUND OF THE INVENTION

The field of the invention is camera cranes. Camera cranes are oftenused in motion picture and television production. The motion picture ortelevision camera is typically mounted on the front end of a crane armwith counterweights at the back end of the crane arm. The crane arm ispivotally supported on a base to allow the crane arm to tilt up and downand pan from side-to-side. The base is typically supported on a cameradolly, wheeled mobile base, or truck.

Telescoping camera cranes have a telescoping arm that can extend andretract, providing far more capability than fixed length crane arms.However, existing telescoping camera cranes generally weigh severalhundred kilograms, which exceeds the safe load carrying capacity ofsmall portable camera dollies. Consequently, for filming in confined orless accessible spaces where only a small portable camera dolly can beused, there are few if any options for using a telescoping camera crane.

Of course, existing telescoping camera cranes can be made smaller whichalso makes them lighter. However, regardless of the size, the cameracrane must be able to consistently hold the camera (and variousassociated payloads such as a remote camera head) in a steady position,even with the arm fully extended. As the camera crane size is reduced,the smaller structural components of the camera crane have reducedcapability to resist unintended or undesirable camera movements, due tobending, flexing, twisting, or vibration. Accordingly, engineeringchallenges remain in designing a lightweight and compact telescopingcamera crane.

SUMMARY OF THE INVENTION

In one aspect, a lightweight camera crane has an outer arm pivotallyattached to a base. A trim weight tray is rigidly attached to a back endof the outer arm. A moving counterweight carriage is supported oncarriage rollers on top of the outer arm. An inner arm is supported onarm rollers within the outer arm. A camera platform is pivotallyattached to a front end of the inner arm for tilt axis movement. Anelectric leveling motor connected to the camera platform via amechanical linkage keeps the camera platform level regardless of thetilt angle of the camera crane. An electric extension motor drivestelescoping extension and retraction movement of the inner arm viachains, belts or cables connected to the counterweight carriage and theinner arm.

The camera crane weighs is lightweight and may be supported on a smallcamera dolly or pedestal. For example, a camera crane having an innerarm with 2 meters of travel weighs about 170 kg. As a result, both thecamera dolly and the camera crane may be lifted and carried by a cameracrew for use in locations otherwise not accessible to heavier cameracranes.

Other aspects and features are shown in the drawings, which show oneexample of how the lightweight camera crane may be designed, and whichare not intended to specify a limit on the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top, rear and right side perspective view of a lightweighttelescoping camera crane.

FIG. 2 is an exploded perspective view of the camera crane as it isshown in FIG. 1.

FIG. 3 is a similar exploded perspective view of major elements of thecamera crane shown in FIGS. 1 and 2, with components removed for purposeof illustration.

FIG. 4 is a side view of the camera crane of FIGS. 1 and 2 with the baseand trim weight platform removed.

FIG. 5A is a rear view of the camera crane of FIG. 4.

FIG. 5B is a view similar to FIG. 5A but with the nose assembly removed,for purpose of illustration.

FIG. 6 is a section view taken along line 6-6 of FIG. 4, with thecounterweight carriage removed.

FIG. 7 is a top view of the crane of FIGS. 1-2, showing the crane withthe inner arm in a partially extended position.

FIG. 8 is a side view in part section of the crane as shown in FIG. 7.

FIG. 9 is an enlarged detail section view of the back end of the craneas shown in FIG. 8.

FIG. 10 is an enlarged detail section view of a portion of thecounterweight carriage as shown in FIG. 8, with covers removed in FIGS.7-10 for purpose of illustration.

FIG. 11 is a top, right and rear perspective view, in part section, ofthe outer arm shown in FIGS. 1 and 2.

FIG. 12 is an exploded top, rear and right side perspective view of theinner arm shown in FIGS. 1 and 2.

FIG. 13 is a top, rear and right side exploded perspective view of thebase shown in FIGS. 1 and 2.

FIG. 14 is a top and front exploded perspective view of the base frameshown in FIG. 13.

FIG. 15 is a front, top and right side perspective view of the motorhousing shown in FIGS. 2 and 9.

FIG. 16 is a section view of the motor housing shown in FIG. 15.

FIG. 17 is an enlarged section view detail of the sprocket and pulleysshown in FIG. 16.

DETAILED DESCRIPTION OF THE DRAWINGS

As shown in FIGS. 1 and 2, a camera crane 20 has a crane arm 22including an outer arm 56 and an inner arm 58 telescopically extendibleinto and out of the outer arm 56. The outer arm 56 is pivotally mountedon a base 24 via axles 26. Handles are attached to the outer arm 56,such as a rear handle 40 and side handles 44, to allow the crane arm 22to be easily grasped, moved, or held into a desired position. A noseframe 50 is rigidly attached, e.g., bolted, onto the front end of theinner arm. The camera (not shown) is attached to the mounting plate 52.The nose frame 50 may be magnesium, to reduce weight. Referring now alsoto FIGS. 3 and 4, one or more tilt motors 112 acting through a tilt geardrive or linkage 114 pivot the mounting plate 52 as required to keep themounting plate (and the camera on the mounting plate) level, regardlessof the tilt angle of the crane arm 22, as described in Chapman U.S. Pat.No. 7,854,555, incorporated herein by reference.

A counterweight carriage 34 rolls on a top surface of the outer arm 56to keep the crane arm 22 balanced as the inner arm 58 extends andretracts. Specifically, as shown in FIGS. 2 and 13, the counterweightcarriage 34 has top rollers 46 which roll on a top surface of the outerarm 56, and side rollers 48 which roll on the sides of the outer arm 56.The counterweight carriage 34 typically carries a fixed number ofcounterweight plates selected so that the crane arm is balancedregardless of the position of the inner arm, with a minimum payload orno payload on the mounting plate 52. The weights on the counterweightcarriage may be changed as needed if the nose frame 50 is replaced witha heavier or lighter nose assembly.

As shown in FIGS. 1 and 2, a trim weight tray 36 is attached to the backend of the outer arm 56. Trim weight plates are added to or removed fromthe trim weight tray to balance the crane arm 22 after the payload isattached to the nose frame 50 and the crane 20 is ready for use. Slidingor rolling trim weights may be provided on the side handles for makingsmall balance adjustments.

Referring now to FIGS. 7-10, an extension motor 102 drives a sprocket104 through a gear drive 96 within a motor enclosure 94 at the back endof the outer arm 56. The gear reduction may have a drive ratio of 2-6,to allow for manually moving the inner arm by back driving the motor. Afirst end of a chain 106 is attached to the back end of thecounterweight carriage 34 via a first chain anchor 80. The chain 106wraps around the sprocket 104 with the other end of the chain 106attached to the back end of the inner arm 58 via a second chain anchor80, as shown in FIG. 10.

As shown in FIGS. 7, 9 and 17, two rear cables 115 run alongside of thechain 106, with one end of each cable attached to the back end of thecounterweight carriage 34 via a cable anchor 78, and with the other endof each cable attached to near the back end of the inner arm. The chainand cable anchors allow tension to be adjusted.

A first end of each of a group of three front cables 110 is attached toa front end of the counterweight carriage 34 via a first cable anchor78, with the cables running over pulleys 82 on the front end of theouter arm 56, and with second end of each front cable 110 attached tothe inner arm 58 via a second cable anchor 78 adjacent to, and in frontof, the first chain anchor 80. The chain 106 may be replaced by a beltand the front cables 110 may be replaced by a chain or belt. Theextension motor 102 is powered via an electrical cable connected tobatteries or other power supply typically carried on the camera dolly.The extension motor 102 may be controlled via a wireless controllercarried by the crane operator, or via a hand control attached ortethered to the crane 22.

As shown in FIGS. 11 and 12, upper roller tracks 70 and lower rollertracks 71 are attached to the sides of the inner arm 58. Left frontrollers 86 and right front rollers 87 are rotatably attached to left andright front plates 84 and 85, respectively, bolted onto the front end ofthe outer arm 56. The left and right front rollers 86 and 87 fit betweenthe upper roller tracks 70 and the lower roller tracks 71. Upper innerrear rollers 72 and lower inner rear rollers 74 are rotatably attachedto roller brackets 76 on opposite sides of the back end of the inner arm58. The rollers may be Torlon® polyamide-imide polymer, providing quietand wear resistant operation. A second pair of left and right frontrollers 86 may optionally be provided at the front end of the outer arm56, providing a total of four front rollers 86.

With the inner arm retracted, the weight of the inner arm, and theweight of the nose assembly and the camera, is supported on the lowerroller tracks 71. As the inner arm 58 extends, the load on the inner arm58 is shifted onto the upper roller tracks 70 supported by the frontrollers 86, with the upper inner rear rollers 72 at the back end of theinner arm rolling on the inside top surface of the outer arm 56. Cablesupports 60 are captive around and roll on the upper roller tracks 70 toprovide intermediate cable support locations for cables running to thecamera on the mounting plate 52.

Referring still to FIGS. 6, 11 and 12, the outer arm 56 may be analuminum extrusion formed as a hollow rectangle with a top channel 90 inthe top wall between left and right top flanges 88 and an internalchannel 92 under the top channel 90. As shown in FIG. 5, the top rollers46 roll on the left and right shoulders 108 of the outer arm 56, betweenthe left and right top flanges 88, with the side rollers 48 rolling onthe sides of the flanges 88. As shown in FIG. 5B, the flanges 88 have anangle section 89. The side rollers 48 may have a flange 49 which fitsunder the angle section 89 to prevent the counterweight carriage 34 fromlifting up off of the top surface of the outer arm 56. Referring toFIGS. 8-10, the chain 106 and the front cables 110 and rear cables 115are positioned within the internal channel 92, providing a more compactdesign.

Turning to FIGS. 1, 2 and 13, a threaded fitting 38, such as a Mitchel™mount fitting, is provided at the bottom of the base 24 for attachingthe base 24 onto the arm of a camera dolly. As shown in FIG. 14, a baseframe 30 is rotatably supported on a center post 160 via pan bearings162, with the pan bearings 162 held in place via a frame cap 164 boltedonto the upper end of the center post 160.

In FIG. 13, the left and right base plates 28 and 32 are bolted onto thesides of the base frame 30. The axles 26 on the outer arm 56 extend intobearings at the upper ends of the base plates, so that the crane arm 22is pivotally attached to the base 24 and can tilt up and down. Anencoder chain 142 extends around a crane arm sprocket 144 fixed to theright side of the outer arm 56 around the axle 26, and around an encodersprocket on a rotary encoder 140 on the right base plate 32. The rotaryencoder 140 senses the tilt angle of the crane arm 22 and provides atilt angle signal to a controller which controls the tilt motors 112 tokeep the mounting plate 52 level as the crane arm 22 tilts up and down.

A tilt brake assembly 120 includes a brake sprocket 126 and a leversprocket 128 both rotatably mounted on the right base plate 32 andconnected via a brake chain 124. An idler 132 maintains tension on thebrake chain 124. A brake lever is rigidly attached to the lever sprocket128. The brake sprocket 126 is mounted on a lead screw thread on atension shaft 138 on the right base plate 32. A brake plate 122 ispositioned between the brake sprocket 126 and the outside of the rightbase plate 32. A brake ring 145 is positioned between the inside of thebase plate and the outer arm. The brake ring 145 may be Delrin acetalresin. The brake sprocket 126 and the lever sprocket 128 and the brakechain 124 are covered via a chain cover 134. Although FIG. 13 largelyshows the right side of the tilt brake assembly 120, the same componentsas described above are provided on the right base plate 32.

A tilt brake lever axle 136 connects the lever sprockets on the left andright sides. Pulling either the left or right brake lever 130 rotatesthe lever sprocket 128, which rotates the brake sprocket 126, causingthe brake sprocket 126 to move inwardly on the tension shaft,compressing the brake ring 145 between the outer arm and the top end ofthe right base plate 32. This movement exerts braking force on bothsides of the outer arm 56, without acting on the axle bearings. The tiltbrake assembly may be used to slow tilt movement of the crane arm 22, orto lock the crane arm at a fixed tilt angle. As shown in FIG. 13, thetilt brake assembly 120 has a minimum width to allow the side weights onthe counterweight carriage 34 to pass over the tilt brake assemblywithout interference.

In FIG. 13, a monitor support 146 is bolted onto the right base plate 32for supporting a monitor providing an image from the camera to thecamera operator and/or the crane operator. The monitor consequently panswith the crane arm 22, allowing the operators to more easily view theimage from the camera continuously. With the monitor in constant viewfrom the side of the crane arm 22, and with controls for the camera andfor the extension motor at or near the back of the crane arm 22, or on ahand held unit, the camera and the crane 20 may be entirely controlledby a single operator. A second monitor support may be provided on theleft base plate 28. The monitor support may extend telescopicallyoutward to allow the monitor to be positioned further to one side of thecrane, as may be desired.

Referring to FIGS. 13 and 14, a pan brake assembly 150 has a splitcollar 152 around the center post 160, which is rigidly attached to thebase frame 30. A pan brake rod 154 extends through the split collar 152and is threaded into followers 158 having left and right hand screwthreads. A pan brake lever 156 is attached to one or both sides of thepan brake rod 154. Turning the pan brake lever 156 drives the followers158 towards each other, causing the split collar 152 to clamp onto thecenter post 160, braking panning movement of the crane arm 22. The panbrake assembly 150 may be used to slow panning movement of the crane arm22 about the base 24 or to lock the crane arm 22 against any panningmovement.

Turning to FIGS. 15, 16 and 17, the sprocket 104 is attached to theoutput shaft 105 of the gear drive 96. The gear drive 96 may have a gearratio which is low enough to allow back driving the extension motor 102.This allows the inner arm to be manually extended or retracted, e.g., bypushing or pulling on the counterweight carriage by hand, if electricalpower is not available. The pulleys 82 alongside of the sprocket 104have bearings supported on a pulley housing 116 attached to the motorhousing 94. Consequently, the radial loading on the output shaft 105 isreduced because only the tension of the chain 106, and not the tensionof the rear cables 115, is applied to the output shaft 105. The load onthe internal shafts and bearings of the extension motor 102 and the geardrive 96 are reduced, which reduces wear and noise. The tension load onthe chain 106 is also reduced as the tension in the rear cables 115offsets a majority of the tension in the front cables 110.

In use, the crane arm 22 is mounted on a camera dolly or pedestal. Indesigns having a two meter telescoping movement, the crane arm 22 islight enough to be lifted by a camera crew. The crane arm 22 cantherefore be mounted on a camera dolly without lifting equipment. Thecrane arm 22 is typically first locked into a horizontal position,either via the tilt brake or via a strut temporarily attached to thebase frame 30 and to the crane arm 22. A camera is attached to themounting plate and the crane arm 22 is balanced as described above. Thecrane arm 22 is positioned as desired via a crane operator grasping thehandles and pushing or pulling the crane arm. The inner arm istelescopically extended using a wired or wireless control which controlsthe extension motor 102. When the motor is actuated to extend, theextension motor 102 turns the sprocket 104 counterclockwise in FIG. 8.The chain 106 pulls the counterweight carriage 34 towards the rear ofthe crane arm 22. Simultaneously, the front cables 110 pull the innerarm forward, extending the inner arm. The extension motor 102 and geardrive 96 may be selected so that they can be readily back-driven, bypushing or pulling on inner arm 58 with a nominal force of e.g., 90 to225 N. This allows the inner arm 58 to be manually telescopically movedin or out, without using the motor.

The arm is retracted by operating the extension motor 102 in the reversedirection, with the chain 106 pulling the inner arm back into the outerarm, and with the front cables pulling the counterweight carriagetowards the front of the crane arm 22. One or more shock absorbers maybe provided on the counterweight carriage or at front and rear stoppositions on the outer arm 56, to prevent the counterweight carriagefrom making a hard impact at the front or rear limit of travel. Theelectronic controller of the extension motor 102 may also be linked tosensors which detect the position of the counterweight carriage, todecelerate the counterweight carriage automatically as it approaches thefront or rear limit of travel. In the example shown with an outer arm 56about length of about 300 cm, the inner arm travel is about 215 cm.

The example shown in the drawings having 2 meters of extension weighsabout 170 kg. Typical crane weights using the design shown are 120 kg to200 kg. The same design principals may of course be used to provide evenlighter designs, having less extension. Since the crane arm 22 has onlya single moving arm, the weight and complexity of additional rollers,cables and other components associated with having two or more movingarms, is avoided. The crane arm 22 also provides a more simple designwhich may be manufactured with fewer components and steps, and which maybe provided at lower cost compared to existing designs. As describedabove, the inner arm 58 is supported within the outer arm only by thefront rollers 86 and the rear rollers 72 and 74, with no intermediaterollers used.

Thus, a novel telescoping camera crane has been shown and described.Various changes and substitutions may of course be made withoutdeparting from the spirit and scope of the invention. The invention,therefore, should not be limited, except to the following claims, andtheir equivalents.

The invention claimed is:
 1. A camera crane, comprising: a base; anouter arm pivotally attached to the base; a trim weight tray rigidlyattached to a back end of the outer arm; a counterweight carriagesupported on the outer arm, on carriage rollers; an inner armtelescopically supported within the outer arm on arm rollers; anelectric extension motor on the outer arm; a first tension elementengaged with the electric extension motor and having a first endattached to the counterweight carriage, and a second end attached to theinner arm; a second tension element having a first end attached to thecounterweight carriage and a second end attached to the inner arm; anose frame rigidly attached to a front end of the inner arm; a mountingplate pivotally attached to the nose frame; and an electric levelingmotor on the nose frame linked to the mounting plate; with the basehaving a left base plate on a left side of the outer arm and a rightbase plate on a right side of the outer arm, with the outer armpivotally attached to the base via left and right axles on the left andright base plates; a left tilt brake assembly on the left base platehaving an upper left tilt brake sprocket co-axial with the left axlestub, a lower left tilt brake sprocket spaced apart from the upper lefttilt brake sprocket, a left tilt brake chain connecting the upper andlower left tilt brake sprockets, and a left tilt brake lever rigidlyattached to the lower left tilt brake sprocket, with movement of theleft tilt brake lever braking pivoting movement of the outer arm on thebase.
 2. The camera crane of claim 1 with the upper left tilt brakesprocket rigidly connected to a brake plate for exerting braking forcebetween the base and the outer arm.
 3. The camera crane of claim 1further including a right tilt brake assembly on the right base platehaving an upper right tilt brake sprocket co-axial with the right axlestub, a lower right tilt brake sprocket spaced apart from the upperright tilt brake sprocket, a right tilt brake chain connecting the upperand lower right tilt brake sprockets, a right tilt brake lever rigidlyattached to the lower right tilt brake sprocket, and a tilt brake axlerigidly connected to the lower left tilt brake sprocket and to the lowerright tilt brake sprocket.
 4. The camera crane of claim 3 with thecounterweight carriage having top weights and side weights, with theside weights having a lower end extending below a bottom surface of theouter arm, and with the tilt brake axle below the lower ends of the sideweights.
 5. The camera crane of claim 1 with the left and right baseplates attached to left and right sides of a base frame rotatablymounted on a center post of the base, further including a pan brakeincluding a split collar around the center post, a pan brake rod linkedto the split collar passing through at least one of the left and rightbase plates, and a pan brake lever on an end of the pan brake rod. 6.The camera crane of claim 1 including upper and lower roller tracks onopposites sides of the inner arm supported on left and right frontrollers at a front end of the outer arm.
 7. The camera crane of claim 6wherein inner arm is telescopically supported in the outer arm only bythe front rollers and upper and lower inner rollers on a back end of theinner arm.
 8. The camera crane of claim 7 further including four upperinner rollers and two lower inner rollers at a back end of the inner armfor rolling on upper and lower inner surfaces of the outer arm.
 9. Thecamera crane of claim 1 wherein the first tension element comprises achain passing around a sprocket on the extension motor, and the secondtension element comprises one or more cables passing over pulleys at afront end of the outer arm.
 10. The camera crane of claim 1 furtherincluding a monitor support attached to the left base plate.
 11. Thecamera crane of claim 1 with the first and second tension elementspositioned in the upper and lower central channels of the outer arm. 12.A camera crane, comprising: a base pivotally attached onto a base plateadapted for mounting on a camera dolly; an outer arm pivotally attachedto the base; a trim weight tray rigidly attached to a back end of theouter arm; one or more pulleys at a front end of the outer arm; acounterweight carriage supported on carriage rollers, on the outer arm;an inner arm telescopically supported on arm rollers within the outerarm; an electric extension motor on the outer arm; a chain extendingaround a sprocket on the electric extension motor, with the chain havinga first end attached to the counterweight carriage, and a second endattached to the inner arm; one or more cables extending around thepulleys and having a first end attached to the counterweight carriageand a second end attached to the inner arm, with a length of the chainand the cable positioned within a channel in the outer arm; a nose framerigidly attached to a front end of the inner arm; a mounting platepivotally attached to the nose frame; an electric leveling motor on thenose frame linked to the mounting plate; first and second upright baseplates on the base, on opposite sides of the outer arm; a first tiltbrake sprocket pivotally attached to the first upright base plate andco-axial with a tilt axis of the outer arm; a second tilt brake sprocketpivotally attached to the first upright base plate and spaced apartfrom, and below, the first tilt brake sprocket; a tilt brake chainconnecting the first and second tilt brake sprockets; a tilt brake leverrigidly attached to the second tilt brake sprocket, with movement of thetilt brake lever actuating a tilt brake to brake pivoting movement ofthe outer arm on the base; and at least one monitor support attached tothe first upright base plate.
 13. The camera crane of claim 12 having aweight of 120 to 200 kg.
 14. A camera crane, comprising: a base; anouter arm pivotally attached to the base; a trim weight tray rigidlyattached to a back end of the outer arm; a counterweight carriagesupported on the outer arm, on carriage rollers; a single inner armtelescopically supported within the outer arm only via front rollers atthe front end of the outer arm and by rear rollers at the rear end ofthe inner arm; an electric extension motor on the outer arm; a firsttension element engaged with the electric extension motor and having afirst end attached to the counterweight carriage, and a second endattached to the inner arm; a second tension element having a first endattached to the counterweight carriage and a second end attached to theinner arm; a nose frame rigidly attached to a front end of the innerarm; a mounting plate pivotally attached to the nose frame; an electricleveling motor on the nose frame linked to the mounting plate; and withthe first tension element comprising a chain, and with the electricextension motor having a motor shaft driving a gear reduction unithaving sprocket engaged with the chain, and with the electric extensionmotor and the gear reduction unit having a gear reduction ratio of 2 to6 to allow the inner arm to be manually back-driven.
 15. A camera crane,comprising: a base; an outer arm pivotally attached to the base; a trimweight tray rigidly attached to a back end of the outer arm; acounterweight carriage supported on the outer arm, on carriage rollers;a single inner arm telescopically supported within the outer arm onlyvia front rollers at a front end of the outer arm and by rear rollers ata rear end of the inner arm; an electric extension motor on the outerarm; a first tension element engaged with the electric extension motorand having a first end attached to the counterweight carriage, and asecond end attached to the inner arm; a second tension element having afirst end attached to the counterweight carriage and a second endattached to the inner arm; a nose frame rigidly attached to a front endof the inner arm; a mounting plate pivotally attached to the nose frame;an electric leveling motor on the nose frame linked to the mountingplate; the electric extension motor including an output shaft and amotor enclosure; a sprocket attached onto the output shaft with thefirst tension element engaged with the electric extension motor via thefirst tension element engaged around the sprocket; the output shaftextending through a pulley supported on a bearing attached to the motorenclosure; and a cable extending around the pulley, with the cablehaving a first end attached to the counterweight carriage and a secondend attached to the rear end of the inner arm.